Food casings used in the processed food industry are generally thin-walled tubing of various diameters prepared from regenerated cellulose, cellulose derivatives, alginates, collagen and the like. Fibrous webs may also be embedded in these food casings and such casings are commonly termed in the art "fibrous food casings". In general, both fibrous and non-fibrous casings have multifunctional uses in that they may be employed as containers during the processing of the food product encased therein and also serve as a protective wrapping for the finished product. In the sausage meat industry, however, the preparation of various types of sausages ranging in size from smaller sausages, such as frankfurters, up to the larger sizes, such as bolognas, usually involves removing the casing from the processed meat prior to final packaging. Peeling the casing from the processed sausage has presented major problems, particularly in the production of frankfurters where large numbers of the product are involved and the desire in commercial operations is to use high-speed, automatic stuffing and peeling machines.
When the casing is removed from the meat mass, there is occasionally a tendency for some meat to adhere to the casing and be torn from the sausage with the casing, thereby causing surface marring of the sausage. In other instances, variations in the meat emulsion formulations or in the processing conditions can result in a degree of adherence of the casing to the product which hinders rapid removal of the casing from the product encased therein. The use of high speed, automatic peeling machines in commercial operations as, for example, disclosed in U.S. Pat. Nos. 2,424,346 to Wilcoxon; 2,514,660 to McClure et al.; 2,686,927 to Greg; and 2,757,409 to Parkers et al., makes it particularly essential that there be minimal resistance to the separation of casing from sausage, or the product will jam at the peeler or go through unpeeled. Less than complete removal of the casing necessitates the expense of hand sorting and peeling.
Heretofore many attempts have been made to provide casings having easy release characteristics. It is known in the art, as disclosed, for example, in U.S. Pat. Nos. 2,901,358 to Underwood et al.; 3,106,471 and 3,158,492 to Firth; 3,307,956 to Chiu et al.; 3,442,663 to Turbak; 3,558,331 to Tarika; and 3,898,348 to Chiu et al., that the application of certain types of coatings to the inside wall of food casings may afford improvement in the release characteristics of the casing from the encased sausage product.
Food casings having good release characteristics sometimes present other problems, unrelated to the release property, prior to, or at the time of, the automatic food stuffing operation. Casings which are generally utilized to encase food product such as vienna sausage, frankfurters and the like, are typically fabricated in continuous lengths, measuring from about 55 feet to 160 feet or longer in length, and from about 7/8 inch to 2-1/2 inches or more in flat width, which are formed into shirred casing sticks. The casing is stored, prior to use, in the form of these shirred or pleated casing sticks measuring 1 to 2 feet in length. Two properties of the shirred casing sticks are particularly important, namely the "coherency" of the stick, which relates to the stick's capacity to maintain its integrity as a shirred stick and not to "break" into multiple shirred pieces, and the "deshirr capacity" of the stick, which relates to the ability to depleat the shirred stick just prior to stuffing without applying excessive force that would cause the casing to tear. It has been found that some release coatings as, for example, disclosed in U.S. Pat. No. 3,451,827 to Bridgeford, when applied to the inside surface of the food casing, interferes with mechanical shirring of the casing or the mechanical stuffing of shirred casing. Other release coatings, such as those disclosed in U.S. Pat. 3,898,348 to Chiu, while providing excellent release properties, at times leave something to be desired in terms of shirred stick coherency.